Superconductor-insulator-superconductor (SIS) mixers for use in millimeter-wave receivers are assembled from several parts. The mixer is a metal block in which a dielectric substrate is mounted. On this substrate is the active circuit, a thin metal film. One major difficulty in the fabrication of the SIS mixers is making the electrical contact between the metal block and this thin film. The substrate must be glued in place and then a contact to the ground connection and the intermediate frequencies (IF) connection made using silver paint, wire bonding, or metal loaded epoxy. This is difficult and tedious. Furthermore, the reliability of the contact is not good, especially since the mixer must be cryogenically cooled for it to work.